As device dimensions shrink, device designers are turning to materials other than silicon, such as III-V semiconductor alloys. Silicon has been used for decades and is well-understood, but the behavior of these new materials is yet to be fully characterized.
Properties of materials can be calculated from ab initio, or first principles, calculations of electronic structures based on quantum physics theories. First principles models can be used to compute thermodynamic and transport properties of pure materials, defects and dopants. Results of first principles calculations are used to drive higher-level calculations, such as kinetic Monte Carlo and continuum calculations. From these, device properties are derived. In order to model the materials, first principles calculations are used to determine fundamental material properties, such as the equilibrium atomic structures and their energies of materials under evaluation. Such fundamental material properties include such quantities as the defect structure and a migration path of the defect, the atomic forces of the atomic structure, positions of one or more atoms of the atomic structure, atomic coordinates of constituent atoms in a unit cell of the atomic structure, the minimum energy of a unit cell of the atomic structure, formation energy of defects, migration energy of defects, entropy of defect formation, entropy of defect migration, defect concentration, defect diffusivity, and so on.
Performing first principles calculations is difficult and costly. Existing methods for structure optimization suffer from slow convergence and occasional incorrect solutions. To solve the issues, laborious human intervention for analysis and tweaking often are required case-by-case. Such intervention can require in-depth understanding of quantum physics and related theories, and can take a person significant amount of time to understand the calculations. Also, it can require manual work to extract physical parameters from results of the first principles calculations. If not done correctly, the ab initio calculation can become stuck in a saddle point of the iteration, or require enormous amounts of time to converge. Alternatively, if done at too large a granularity, the calculation can result in low accuracy.
It is desirable to provide a computer system with a control module that can optimize utilization of the computing resources, while at the same time automatically sidestepping local optima to guide the calculations toward global optima at high accuracy. Such a computer system can determine the basic properties of new or previously uncharacterized materials, thereby greatly improving both the computer system and the technology for evaluating new materials for use in future integrated circuit devices or their manufacture.